We propose to conduct studies of the para-crystalline so called "hexagonal" membranes of the outermost cell of the mammalian urinary bladder epithelium by electron microscopic (EM), physical chemical and biophysical approaches. The EM studies will be aimed first at better understanding the nature of the approximately 120 angstrom units globular intramembrane particles (IMPs) seen in the EF faces of the bladder membranes by freeze-fracture-etch (FFE) electron microscopy. Similar studies will be done on the purple membrane of H. halobium and erythrocyte membranes aimed at classifying the IMPs of these membranes into primarily protein and lipid groups. Approximately 120 time 55 angstrom units external protein particle of the bladder membrane will be extracted with EGTA and characterized. The membrane fluidity will be studied before and after extraction by a fluorescent probe method and FFE electron microscopy. A phosphorous NMR study will be conducted aimed at better understanding the physical state of the lipid in the bladder membrane. The three dimensional structure of the bladder membrane will be analyzed by low dose electron microscopy in negative stain to less than 20 anstrom units resolution. The bladder membrane will be studied by wide angle and low angle x-ray diffraction methods. A special technique will be developed to obtain aggregates of the membrane possessing centro-symmetry.